title: Age thresholds for changes in semen parameters in men.
abstract: OBJECTIVE
  To determine whether age thresholds for elements of semen quality exist.
  
  
  METHODS
  Retrospective analysis (covariance and point-change analysis) of results of 4,822 semen analyses and 259 fluorescence in situ hybridization (FISH) analyses.
  
  
  METHODS
  Reference laboratory within an infertility clinic.
  
  
  METHODS
  A total of 5,081 men aged 16.5-72.3 years.
  
  
  METHODS
  None.
  
  
  METHODS
  Ejaculate volume, sperm concentration, sperm motility, sperm motion parameters, strict morphology, and results of FISH analysis.
  
  
  RESULTS
  Measured parameters of ejaculates did not change before 34 years of age. Immediately thereafter, total sperm numbers (and total motile) declined. Sperm concentration and the proportion of sperm of normal morphology declined after 40 years. Sperm motility and progressive parameters of motile sperm fell after 43 years and ejaculate volume after 45 years. The ratio of Y:X-bearing sperm in ejaculates decreased only after 55 years.
  
  
  CONCLUSIONS
  Our findings project a declining likelihood of pregnancy following intercourse with men >34 years old, independent from the woman's age and increasing with advancing age. Age-related mechanisms associated with this oligoasthenoteratozoospermic progression are discussed.
authors.affiliation: Reproductive Technology Laboratories, Los Angeles, California; Utah Fertility Partners, Pleasant Grove, Utah. Electronic address: bstone@californiafertilitypartners.com.
authors.forename: Bronte A
authors.initials: BA
authors.lastname: Stone
authors.forename: Allyse
authors.initials: A
authors.lastname: Alex
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Werlin
authors.forename: Richard P
authors.initials: RP
authors.lastname: Marrs
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000235:genetics / Q000473:pathology*; D000704:Analysis of Variance; D048430:Cell Shape; D041321:Chromosomes, Human, X; D041322:Chromosomes, Human, Y; D005260:Female; D005298:Fertility; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007248:Infertility, Male / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D016018:Least-Squares Analysis; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010331:Paternal Age; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D012307:Risk Factors; D055101:Semen Analysis / Q000379:methods; D013076:Sperm Count; D013081:Sperm Motility; D013094:Spermatozoa / Q000473:pathology*; D055815:Young Adult
keywords: Aging and oligoasthenoteratozoospermia; CASA; human semen; primary sex ratio; sperm morphology